Finger-prick machine inaccurate readings

[CallMeGinger]

When I was first diagnosed with antiphospholipid syndrome several years ago, I was put on warfarin and had to go weekly for finger-prick test. My readings were up and down; all over the place!

There is an app "MyINR" which has the ability to show a graph. Made an interesting mountain range!!

I consulted Dr Google and found many interesting forums. After reading several, I told my GP that maybe the machine was not for me.

I had two instances of finger-prick and blood draw, each occasion within an hour of each other. (Hope that makes sense.) Results varied so much, it was obvious I had to go the blood test route from then on.

Now I only ever go weekly if I have been taking other medications for different health reasons.

Works for me.

[KellyInTexas Administrator]

Hello,

I’m glad you’ve joined our forum.

I am also one of the , “unlucky ones.”

APS antibodies react with the reagents on the back of the test strips, so explained the Roche technician to me.

It is advised to do , “ parallel tests” at the same time - a blood ( or vein ) draw against the finger prick test to see the difference. Keep careful notes.

See what your difference is. Is it consistently the same? If so, then you can know your true vein value.

Mine was sadly not.

If just something patients can try and see- with careful observation.

It should never replace vein draws all together- it can just be an aid, or a guide if the patient is predictably congruent with their offset from vein value.

Sorry it didn’t work for you- it’s very handy for patients when it does.

[Ray46]

The issue with finger-prick testing being inaccurate for certain APS patients (esp. LA +ve) has been known for years, unfortunately it hasn't yet got widely enough known to make it's way into standard national (eg. NICE) guidelines (though I must admit I haven't checked recently).

All APS patients _should_ have parallel vein/finger-prick testing until accuracy is established, if it isn't then only vein should be used, if it is (and it varies patient to patient, and with time) it should be rechecked with parallel testing every few months. This _should_ be automatic, but, several years ago I had to ask for it - I wouldn't have to now, as they definitely now have a clue in my area, and possibly I wouldn't have gone long without it before someone with a clue looked at my case if I hadn't had a clue myself and asked.

For me it took 2 maybe three months of parallel testing before dropping the vein tests, and six-monthly re-checks after that - but under the system I _always_ have the option to get a vein check instead and sometimes I do.

Constant vein testing has the downside that it ****s up your veins, eventually (or sooner if the needle jockeys aren't very good) they will become unusable. With blood draws every few months, my elbows are going to last much much longer, every week or two was too little recovery time and on occasions I was going in with surface bruising still visible and painful on both elbows from previous tests so who knows what state the veins underneath were in - not good. Once your elbows are blown the action moves to hands or wrists (more painful, trust me, been there), and allegedly then to feet and places you don't want to know about.

It is all a balancing act - we need to get accurate tests, but we also need to look after our blood vessels because our circulation has enough problems from the disease.

[MaryF Administrator]

HI, you have had a very detailed reply from KellyInTexas who clearly has experience with this, I have never been on Warfarin so have no personal experience. Obviously the home testing machines suit many people, as long as they continue with their clinic readings alongside their home test results, so that any differences can be logged to see if a pattern occurs. I am pleased that your visits to the clinic are working well for you. MaryF

[Holley]

Are you positive for the Lupus Anticoagulant by any chance? When I first got diagnosed, I had a home machine & brought it with me to the hematologist's office to see if the results I got were the same. They were wayyyyy off. The machine was flashing an alert message, whereas my vein draw was within range. My hematologist called the company and they told her that it wasn't recommended for people w/ LA. Apparently, LA interferes with the reagent the machine uses. I know there are many people on this forum w/ LA and they successfully test at home.